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Self-powered implantable biomedical devices that provide continuous, real-time sensing, monitoring, and various other vital health functions will only be possible through the development of novel power sources that can harvest energy from the implant's surroundings, in vivo. A variety of energy sources in the human body such as limb articulation, respiration, and heartbeat can provide sufficient power for small biomedical devices. However, the development of in vivo energy harvesting devices into useful electrical power is still in infancy. In this project, we propose to explore innovative nanotechnology to develop ultrathin, lightweight, stretchable and bio-compatible piezoelectric polymer membranes with tunable modulus that can efficiently and discreetly convert the nano-/microscale mechanical energy found in human body to electrical energy, and thereby realize a self-sufficient power supply for implantable biomedical devices. This project builds on the PI (Wang)'s recent development of flexible nanogenerator (NG) - a novel approach for effectively converting mechanical energy into electric energy using polymeric piezoelectric nanomaterials. The Co-I (Cai) has >10 years of experience with in vivo imaging studies and surgical procedures in small animals. The Co-I Dr. Kohmoto specializes in all areas of clinical cardiac surgery and cardiac physiology, and will oversee and perform the advanced surgical procedures needed in the proposed work. Together they form a synergistic team with complementary expertise to design, investigate, and optimize the proposed implantable NGs both ex vivo and in vivo.
In Specific Aim 1, we will fabricate flexible membranes from polyvinylidene fluoride (PVDF) with a sponge-like internal mesoporosity. The pore dimension and density will be controlled to engineer the membrane's mechanical and piezoelectric properties, and thus to maximize the mechanical energy absorption and conversion.
In Specific Aim 2, we will investigate and optimize the morphology-related capability of harvesting bio-mechanical energy in simulated in vivo conditions. The encapsulation material and electric circuit will be studied to minimize the stray current from NGs.
In Specific Aim 3, we will improve the long-term stability of NG membrane on muscle/tissue surfaces via a series of strategies such as scar tissue growth, suture- and pin hole-assisted attachment. The static and dynamic adhesion stability, as well as the as well as potential inflammation and biofouling issues will be investigated and optimized.
In Specific Aim 4, the morphology-related capability of harvesting bio-mechanical energy from limb movement, heartbeat, and diaphragm expansion will be studied in vivo using mice or rats. This research will overcome the yet insurmountable challenges of fabricating biocompatible piezoelectric polymer nanostructures and establish a new capability of extracting useful electrical energy from the human body while resulting in minimal impact on the organ's normal functions. The success of this project will make significant contribution to the advancement of the power components of current life-saving implantable devices by reducing the size, lowering the energy density, minimizing the protection package, and resolving safety concerns of the battery systems.

Public Health Relevance

This project aims to explore innovative nanotechnology to develop ultrathin, lightweight, and stretchable and bio- compatible piezoelectric polymer membranes with tunable modulus that can efficiently and discreetly convert the nano-/microscale mechanical energy found in human body to electrical energy. Flexible membranes with a sponge-like internal mesoporosity are proposed and their morphology-related properties and performance will be studied and optimized both ex vivo and in vivo to realize a self-sufficient power supply for implantable biomedical devices (focusing on practically charging/powering a pacemaker).